From 7cfae909af95fc2a633a0aa25e5d644677fe4a52 Mon Sep 17 00:00:00 2001
From: ennewalker <ennewalker@c06c8d41-db1a-0410-9941-cceddc491573>
Date: Sat, 19 Jul 2008 16:02:35 +0000
Subject: Applying r6609 to 0.4.

git-svn-id: https://crawl-ref.svn.sourceforge.net/svnroot/crawl-ref/branches/stone_soup-0.4@6610 c06c8d41-db1a-0410-9941-cceddc491573
---
 crawl-ref/source/acr.cc      |  9 +++++++--
 crawl-ref/source/monstuff.cc | 41 +++++++++++++++++++++++++++++++++--------
 crawl-ref/source/monstuff.h  |  2 ++
 crawl-ref/source/player.cc   |  8 +++++---
 crawl-ref/source/player.h    |  2 +-
 5 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/crawl-ref/source/acr.cc b/crawl-ref/source/acr.cc
index 3dcb424d40..4ee02b279d 100644
--- a/crawl-ref/source/acr.cc
+++ b/crawl-ref/source/acr.cc
@@ -4257,13 +4257,15 @@ static void _move_player(int move_x, int move_y)
         return;
     }
 
+    coord_def mon_swap_dest;
+
     if (targ_monst != NON_MONSTER && !mons_is_submerged(&menv[targ_monst]))
     {
         monsters *mon = &menv[targ_monst];
 
         if (can_swap_places && !beholder)
         {
-            if (swap_places( mon ))
+            if (swap_check(mon, mon_swap_dest))
                 swap = true;
             else
                 moving = false;
@@ -4291,9 +4293,12 @@ static void _move_player(int move_x, int move_y)
     {
         you.time_taken *= player_movement_speed();
         you.time_taken /= 10;
-        if (!move_player_to_grid(targ_x, targ_y, true, false, swap))
+        if (!move_player_to_grid(targ_x, targ_y, true, false, swap, swap))
             return;
 
+        if (swap)
+            swap_places(&menv[targ_monst], mon_swap_dest);
+
         you.prev_move_x = move_x;
         you.prev_move_y = move_y;
 
diff --git a/crawl-ref/source/monstuff.cc b/crawl-ref/source/monstuff.cc
index d4c0dd213c..70ce9ea013 100644
--- a/crawl-ref/source/monstuff.cc
+++ b/crawl-ref/source/monstuff.cc
@@ -1795,6 +1795,37 @@ static bool _habitat_okay( const monsters *monster, dungeon_feature_type targ )
 // when the player is over lava or water (if the player wants to
 // swap pets to their death, we can let that go). -- bwr
 bool swap_places(monsters *monster)
+{
+    coord_def loc;
+    if (swap_check(monster, loc))
+    {
+        swap_places(monster, loc);
+        return true;
+    }
+    return false;
+}
+
+// Swap monster to this location.  Player is swapped elsewhere.
+bool swap_places(monsters *monster, const coord_def &loc)
+{
+    ASSERT(map_bounds(loc));
+    ASSERT(_habitat_okay(monster, grd(loc)));
+
+    mpr("You swap places.");
+
+    mgrd[monster->x][monster->y] = NON_MONSTER;
+
+    monster->x = loc.x;
+    monster->y = loc.y;
+
+    mgrd[monster->x][monster->y] = monster_index(monster);
+
+    return true;
+}
+
+// Returns true if this is a valid swap for this monster.  If true, then
+// the valid location is set in loc.
+bool swap_check(monsters *monster, coord_def &loc)
 {
     int loc_x = you.x_pos;
     int loc_y = you.y_pos;
@@ -1859,14 +1890,8 @@ bool swap_places(monsters *monster)
 
     if (swap)
     {
-        mpr("You swap places.");
-
-        mgrd[monster->x][monster->y] = NON_MONSTER;
-
-        monster->x = loc_x;
-        monster->y = loc_y;
-
-        mgrd[monster->x][monster->y] = monster_index(monster);
+        loc.x = loc_x;
+        loc.y = loc_y;
     }
     else
     {
diff --git a/crawl-ref/source/monstuff.h b/crawl-ref/source/monstuff.h
index 8cebd84d8f..b9ac6c99d3 100644
--- a/crawl-ref/source/monstuff.h
+++ b/crawl-ref/source/monstuff.h
@@ -159,6 +159,8 @@ monsters *choose_random_monster_on_level(
  * called from: acr
  * *********************************************************************** */
 bool swap_places(monsters *monster);
+bool swap_places(monsters *monster, const coord_def &loc);
+bool swap_check(monsters *monster, coord_def &loc);
 
 
 /* ***********************************************************************
diff --git a/crawl-ref/source/player.cc b/crawl-ref/source/player.cc
index cfa61aadd7..1611f4330e 100644
--- a/crawl-ref/source/player.cc
+++ b/crawl-ref/source/player.cc
@@ -106,8 +106,9 @@ static void _attribute_increase();
 // stepped     - normal walking moves
 // allow_shift - allowed to scramble in any direction out of lava/water
 // force       - ignore safety checks, move must happen (traps, lava/water).
+// swapping    - player is swapping with a monster at (x,y)
 bool move_player_to_grid( int x, int y, bool stepped, bool allow_shift,
-                          bool force )
+                          bool force, bool swapping )
 {
     ASSERT( in_bounds( x, y ) );
 
@@ -122,8 +123,9 @@ bool move_player_to_grid( int x, int y, bool stepped, bool allow_shift,
     ASSERT( you.can_pass_through_feat( new_grid ) );
 
     // Better not be an unsubmerged monster either.
-    ASSERT(mgrd[x][y] == NON_MONSTER
-           || mons_is_submerged( &menv[ mgrd[x][y] ] ));
+    ASSERT(swapping && mgrd[x][y] != NON_MONSTER ||
+           !swapping && (mgrd[x][y] == NON_MONSTER
+                         || mons_is_submerged( &menv[ mgrd[x][y] ])));
 
     const int cloud = env.cgrid[x][y];
     if (cloud != EMPTY_CLOUD)
diff --git a/crawl-ref/source/player.h b/crawl-ref/source/player.h
index a1bd79ac52..b5c3a0bc39 100644
--- a/crawl-ref/source/player.h
+++ b/crawl-ref/source/player.h
@@ -28,7 +28,7 @@ enum genus_type
 };
 
 bool move_player_to_grid( int x, int y, bool stepped, bool allow_shift,
-                          bool force );
+                          bool force, bool swapping = false );
 
 bool player_in_mappable_area(void);
 bool player_in_branch( int branch );
-- 
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